Conventional articles of athletic footwear include two primary elements, an upper and a sole structure. The upper provides a covering for the foot that comfortably receives and securely positions the foot with respect to the sole structure. The sole structure is secured to a lower portion of the upper and is generally positioned between the foot and the ground. The sole structure may provide cushioning, traction, and wear resistance. Accordingly, the upper and the sole structure operate cooperatively to provide a comfortable structure that is suited for a wide variety of activities.
Known sole structures have incorporated multiple layers that are conventionally referred to as an insole, a midsole, and an outsole. The insole is a thin, compressible member located within the upper and adjacent to a plantar (i.e., lower) surface of the foot to enhance footwear comfort. The midsole, which is conventionally secured to the upper along the length of the upper, forms a middle layer of the sole structure and is primarily responsible for attenuating ground reaction forces. One known midsole is primarily formed from a resilient, polymer foam material that extends throughout the length of the footwear. In addition to polymer foam materials, existing midsoles have other elements, for example, one or more fluid-filled bladders and moderators. The outsole forms the ground-contacting element of footwear and is usually fashioned from a durable, wear-resistant material that includes texturing to improve traction.
Athletic activities may require frequent and quick lateral bodily movements. Sports such as tennis and basketball are examples of athletic activities which require such dynamic lateral movements. The lateral movements require a secure foot plant to maintain stability. Without a secure footing, injuries can occur. Therefore, when performing such athletic activities, footwear which will provide lateral constraint for the foot during such lateral movements is highly desirable. Hence, in order to reduce the risk of injuries, footwear to be worn during such activities should incorporate features that emphasize lateral constraint. While lateral constraint is one factor to be considered in designing athletic footwear, another factor is the weight of the athletic footwear. In general, it is desirable to make the athletic footwear lightweight. Therefore, it would be desirable for an article of athletic footwear to be lightweight while still providing adequate lateral constraint.
Particular objects and advantages will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain embodiments.